Populations of spleen cells enriched for antigen specific cells have been prepared from virgin and immune animals. These populations contain 20-30% antigen binding lymphocytes. These cell populations will now be utilized for correlating cell surface events with lymphocyte function. Thus, such populations will be incubated with thymus dependent and independent antigens and, in addition toleragens. The immune responsiveness of the populations will then be analyzed both for proliferation and antibody formation. At the same time, other aliquots of the cells will be analyzed to determine the distribution and fate of the antigen specific receptors and other markers on the cell surface. The combined approach utilizing functional analysis on the one hand and the behavior of critical cell surface molecules on the other should lead to new insights into the cell surface events responsible for triggering versus activation.